I had a call from an old SCO Unix customer this week. There
aren't many of those old systems left now - more than you'd
probably think, more than there should be, but far less than there
were just a few years back. I think you still have a good chance
of finding a few SCO boxes in any city, but it's getting harder..
Anyway, this customer called because two printers were not working.
I hadn't seen him in several years (that's the nice thing about these systems:
they do run and run and run without attention) but I did remember
that he had serial printers. I couldn't remember much else so after
a small attempt at trying to help him out by phone, we decided I had
better drive down to see the situation first hand.
When I walked in this morning, some memories flooded back. First
of all I could see that a Digiboard C/Con handled the serial ports
and the screen display on one of the Windows boxes reminded me that
this was a custom point of sale app that I had never seen or even
heard of before or since. I remembered that we'd had some trouble
with that before but as this was just printers I didn't think
that would be an issue today.
So, to the printers. Which ones didn't work? My customer
pointed at an HP Laser. I logged in and did an "lpstat -v" and saw that
printer was defined on /dev/ttya12 and that no other printers were
defined at all. Oh, yeah: more memories: the app prints directly
to device ports. So, what's wrong with ttya12?
Nothing, as it turns out. I could see the back end of the laser from
where I stood and the only thing plugged into it was a parallel cable.
Hmmm.. I walked closer and saw that a tangle of cables came down from
the ceiling. My bet was that we'd find a serial adaptor at the end
of one of them and sure enough, after fishing around under the desks,
we found it, plugged it in and printing to the laser printer worked
yet again. That was easy.
Next? An Oki 3410. I got my tone generator from the car and traced
it back to ttya11. I tried "date > /dev/ttya11" and the printer spit
out a line of garbage. Baud rate wrong? Nope, but when I did the
config test page I noticed more was wrong: the printing started mid page.
That's not a system problem, that's a printer hardware issue. "That's OK",
said my customer, "I have another". And so he did. So I pulled the serial
card from the old printer and put it in the new. Unfortunately the
printer still spewed garbage.
Bad serial card? Nope, I moved it to ttya13 and that "date" printed
fine. So it's the Digi acting up at ttya11. Now what? We can't
change the app because no one knows how. I remembered having pawed
through its menus before and never finding the magic printer configuration
page.. looks like we're out of luck, have to buy a new Digi..
Don't be silly. This is Unix. I added the following to
an rc.d startup file:
ln /dev/ttya13 /dev/ttya11
That's all it takes. The app opens ttya11, but that's actually ttya13.
This is a 16 port Digi supporting only three
printers: it will have to lose a lot more ports before we need to
replace it. Why waste money on a system that is unlikely to remain
in use much longer?
As I packed up to leave, I reminded my customer that he is living
on borrowed time. Someday he will have a crash or problem that
I cannot fix so easily. It's way past time to move to some other
POS application. He agreed and promised to look into it.
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